fix iphone

document.addEventListener('touchend', function(){
    console.log(window.scrollY);
    var header = document.getElementById('header');
    header.style.top = window.scrollY;
    var footer = document.getElementById('footer');
    console.log(footer.clientHeight);
    footer.style.top = window.scrollY + screen.height - 44 - footer.clientHeight - 20;                                                                                 
});